Gas turbine engines utilize a compressor section to compress input air. The compressor section provides the compressed air to a combustor. The combustor ignites a mixture of the compressed air and fuel. The resultant combustion gasses are expelled from the combustor into a turbine section. The expansion of the combustion gasses through the turbine section drives multiple stages in the turbine section to rotate. The stages within the turbine section are each connected to at least one shaft, and drive the shaft to rotate along with the turbine section.
The rotation of the shaft is, in turn, utilized to drive the rotation of the compressor section. In a geared turbofan example, the rotation of the shaft further drives rotation of a fan, with the fan being disposed fore of the compressor section and providing air to a primary flowpath through the compressor section, the combustor, and the turbine sections and to a bypass flowpath that bypasses the compressor section, combustor and turbine section. A gear allows the shaft to drive the compressor section at a first speed and the fan at a second speed.
Developments in turbine engine design and component materials allow previously low speed turbine portions, relative to a remainder of the turbine, to have substantially increased rotational speeds. As the turbine rotation is utilized to drive the compressor systems, the increased speed of the lower speed turbine causes an increased rotational speed of the compressors, absent further modifications to a standard engine design.